Wallpaper math gets tricky with pattern repeats and room dimensions. This calculator figures out how many rolls you need based on your wall size and the wallpaper's pattern repeat, so you don't end up one roll short mid-project.
Room Dimensions
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Openings
Roll Specifications
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Scenario: You're wallpapering a 12 ft x 10 ft powder room with 9 ft ceilings and 1 door. The rolls are 20.5 inches wide and 33 ft long, with a 12-inch pattern repeat.
Result: Wall area is 396 sq ft. Subtract 1 door (21 sq ft) for 375 sq ft of net wall area. With a 12-inch pattern repeat, each strip is cut at 9 ft (the wall height), and each roll yields 3 usable strips covering about 46.1 sq ft. You need 9 rolls.
It depends on the wall size, roll dimensions, and pattern repeat. A 12 ft wide by 8 ft tall wall with a standard roll (20.5 in wide, 33 ft long) and no pattern repeat needs about 2 rolls. Large pattern repeats can nearly double the number of rolls required.
The pattern repeat is the distance before the design repeats vertically. When hanging strips side by side, you have to shift each strip up or down to align the pattern, which wastes wallpaper. Larger repeats mean more waste per strip.
Yes, order at least 1 extra roll. Dye lots vary between print runs, so if you need more later it may not match perfectly. Having a spare also covers mistakes during installation.
Don't do it. Old wallpaper can bubble, peel, or create an uneven surface under the new layer. Strip the old paper first, clean the wall, and apply a wallpaper-specific primer before hanging the new stuff.
Want to learn more before you start your project?
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